Aqueous rinse-aid compositions for use in the home or in industrial/institutional applications following the washing of kitchen utensils long have been known and are commercially available. Such compositions promote rapid draining after the washing is complete and serve to yield easily dryable dishes through the modification of surface tension so that the wash liquid readily flows away. The rinse-aid compositions offer considerable savings in labor to restaurants and institutions where large quantities of dishes and tableware are routinely washed and dried as expeditiously as possible while fully utilizing the finite level of equipment and space that is available. In the past, such rinse-aid compositions commonly have included a surfactant and a hydrotrope (e.g., an anionic hydrotrope) in order to further increase the solubility of the surfactant in water. The hydrotrope commonly adds appreciably to the cost of producing the desired rinse-aid composition particularly when it is present in a large concentration. Rinsing preferably is conducted with vigor in order to increase its effectiveness, and preferably is conducted at elevated temperatures that will better facilitate the removal of remaining traces of the liquid from the surfaces of hot tableware and dishes via volatilization. Also, it is desired that the rinse-aid composition minimize the formation of visually unattractive spots and/or film on the dishes and tableware. However, vigorous rinsing conditions commonly lead to increased foaming which may promote objectionable spotting and film formation. Also, some previously available rinse-aid compositions exhibit stability problems upon storage particularly if heat such as is common in a kitchen environment is encountered prior to use. This can lead to a lack of homogeneity and erratic rinse results when the use of the resulting composition is attempted by kitchen workers without due regard to instability that may have occurred in the rinse-aid composition that is being provided for their use.
Representative nonionic surfactants are disclosed in U.S. Pat. Nos. 4,306,987; 4,411,810 and 4,438,014. Additionally, commonly assigned U.S. Pat. No. 4,272,394 discloses a surfactant composition comprising a blend of nonionic surfactants. Representative previously available rinse-aid compositions are disclosed in U.S. Pat. Nos. 3,082,172; 3,563,901; 4,443,270; and 4,678,596. See also, the article by Jay G. Otten and Christine L. Nestor, entitled "Anionic Hydrotropes for Industrial and Institutional Rinse Aids", JAOCS, Vol. 63, No. 8, Pages 1078 to 1081 (August 1986).
Commonly assigned U.S. patent application Ser. No. 08/261,145 to the same inventors as named herein entitled "Improved Dishwashing Composition Comprising a Blend of Nonionic Surfactants" is filed concurrently herewith.
It is an object of the present invention to provide an improved aqueous rinse-aid composition that is relatively stable upon storage and is suitable for use at a temperature of up to at least 180.degree. F.
It is an object of the present invention to provide an improved aqueous rinse-aid composition that is suitable for use with vigorous application at a temperature of up to at least 180.degree. F. in the absence of excessive foaming.
It is an object of the present invention to provide an improved aqueous rinse-aid composition wherein in a preferred embodiment the usage of a high concentration of a hydrotrope is unnecessary.
It is an object of the present invention to provide an improved aqueous rinse-aid composition that can be utilized in the absence of excessive spotting and film formation on the tableware and dishes following rinsing.
These and other objects and advantages of the claimed invention will be apparent to those skilled in the art from the following detailed description and appended claims.